1. Field of the Invention
The present invention relates to an image forming apparatus that can control the exposure amount.
2. Description of Related Art
As a conventional image forming apparatus of this kind, for example, there is known an apparatus disclosed by Japanese Patent Laid-Open Publication No. 2004-70010. In this image forming apparatus, a glossiness detector for detecting the glossiness of an image on a sheet is disposed downstream of a fixing device with respect to a sheet feeding direction. The image forming apparatus forms a patch image representing a gradation pattern of three gray levels, which are greatly different in the amount of adherent toner, as a test pattern for glossiness measurement. The glossiness detector detects the glossiness of each patch. The image forming apparatus changes parameters for image formation such that the glossiness differences between the gray levels can be minimized.
In a conventional image forming apparatus, it is intended to prevent a decrease in glossiness of an output image by applying parameter changes to the whole image. Depending on the pattern of the image, for example, whether or not it has spatial periodicity, however, there may be problems, such as excessive toner supply, as well as a decrease in glossiness.